<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框样式</title>
    <style>
        #username{
            border:1px red solid;
            /*border-left:none;*/
            /*border-right:none;*/
            /*border-top:none;*/
            border-radius:20px;
        }
        .mydiv{
            width:700px;
            height:55px;
            background-color:#DDFFFF;
            border-left-width:10px;
            border-left-color:red;

        }
    </style>
</head>
<body>
用户名<input type="text" id="username"><br>
<div class="mydiv">
    打火山凤凰算法四分
</div>
</body>
</html>